Merging CVS, which has 10,000 retail clinics and pharmacies, with Aetna means more health services will likely move out of doctors' offices to store-based providers across the nation. Pharmacies already provide vaccinations and blood pressure checks. Now, they could offer one-stop shopping for insurance and certain diagnostic services.

On-site lab work and diabetes counseling are two other possibilities, said Larry Merlo, CVS Health president and CEO. Customers should also expect lower prices, Merlo said. "We know we can make health care more affordable and less expensive," Merlo told The New York Times. "We think of it as creating a new front door to health care in America."

Others aren't convinced this is a win-win for the general public. Some fear that less competition will drive up drug prices. Others worry that consumers insured by Aetna might be restricted in where they can get health care or fill prescriptions.